When it rains on unimproved natural land, the rain and stormwater runoff is either absorbed into the soil or moves along the surface of the land, moving downward towards creeks and rivers. However, as areas become more densely populated, this natural dispersion of rain and stormwater is altered by the man-made improvements, for example, parking lots, roads, and buildings. This leaves less open ground surface to absorb the rain and adds to the stormwater runoff.
In many cities, stormwater sewers are constructed to handle the large amount of stormwater runoff that comes off of the buildings, parking lots, and roads. The stormwater sewers route the water to creeks and drainage ditches, which form the tributaries to larger rivers. However, many cities do not have a stormwater sewer system; therefore, there is no pathway for disposing of the stormwater runoff coming from the buildings, parking lots, roadways, etc.
Common ways of treating storm water involve installing a curb-cut on a side of a street and allowing the storm water to flow out into a rain garden. However, debris can build up and cause the storm water to by-pass the curb cut before the rain garden is full of storm water. In addition, accumulated sediment in the rain garden can smother the existing plants and is unsightly. For example, turf strips along the curb-cut are often ineffective and require exhaustive raking and annual replacement. Rock inlets also lose their effectiveness rapidly without frequent labor intensive cleaning. Alternative structures, for example, chambers filled with porous media and underdrains, can be cost prohibitive and may fail resulting in flooding the rain garden with debris, which requires extensive clean-up.
What is desired is a device that can remove debris and sediment from storm water and allow the treated storm water to enter a storm water receiving feature, for example, a rain garden.